Primary Open Angle Glaucoma and Cataracts Clinical Trial
Official title:
A Randomized, Double-Masked Clinical Trial of Phacoemulsification Compared With Phacoemulsification and Micro-Bypass Stent Implantation in Patients With POAG
This was a prospective, double-masked, 15-month clinical trial comparing efficacy of phacoemulsification alone to combined phacoemulsification and implantation of the iStent® trabecular micro-bypass stent in patients with primary open-angle glaucoma.
This was a prospective, randomized open-label study of 36 patients with POAG scheduled to
undergo phacoemulsification with intraocular lens implantation ("cataract surgery").
Patients were randomized 2:1 to receive either cataract surgery alone (control group) or
cataract surgery and iStent implantation (combined surgery group).
Implantation of the study stent occurred after cataract extraction and IOL insertion using
the same small, temporal, clear-corneal incision (approximately 3 mm) used to perform
phacoemulsification and IOL placement. The study stent was guided into Schlemm's canal using
ab-interno gonioscopy (using a Swan-Jacobs gonioscope). (Figure 1) If no complications
occurred during phacoemulsification, acetylcholine was injected in the anterior chamber
after the IOL implantation to constrict the pupil. The anterior chamber was then filled with
a viscoelastic agent to reform the anterior chamber and provide more clearance in the angle.
The anterior chamber was traversed with the applicator (the implant was on the tip of
applicator) and the trabecular meshwork located. The leading edge of the device was gently
slid through the trabecular meshwork and into Schlemm's canal at the nasal position (3 to 4
o'clock for the right eye; 9 to 8 o'clock for the left eye) with the tip of the implant
directed inferiorly. If difficulty was encountered with the insertion at the primary
location, we tried inserting about 0.5 clock hour inferiorly; and continued to move
inferiorly as needed for subsequent attempts. Next, the device was released by pushing the
button on the applicator, position of the stent was verified and the applicator was
withdrawn.
The patients were instructed to discontinue all glaucoma medications after surgery. Standard
post cataract extraction antibiotic and anti-inflammatory drug regimen was prescribed.
Target pressure for each patient was determined prior to study entry. Following the assigned
procedure, any patient with an IOP (as measured between 8 and 10 AM) that was greater than 2
mm Hg over their target was instructed to return twice in the following three days for
re-measurement of their IOP. If the patient's IOP was > 2 mm Hg over their target pressure,
ocular hypotensive agents were added. The medications were added in a pre-set schedule, with
beta-blockers first, angiotensin-converting enzyme (ACE) inhibitors second, and
prostaglandins third. If, however, on the third consecutive visit the patient's IOP was
within 2 mm Hg of target, patient re-entered the normal visit schedule. Investigators were
masked to treatment assignment both when measuring IOP and when determining when or if to
add medications.
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Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Treatment